71 cuda front valance mounts

[culp71]

All,
looking for some pics or description to guide me in the correct direction..
on a 71 cuda, inner edge of frame rail horns seem to have a square hole and a round for mounting front lower valance, but how?
any help for what should be there, how it attaches and what goes into these holes, as they are not threaded or the correct size for simply a bolt.

thanks

[anlauto]

It's a clip nut.... You put a clip nut in the square hole lining the threads up with the round hole, then use a 1/4 20 bolt through the valance into the frame.